Nitric oxide inhibitory potential of Curcuma angustifolia Roxb. essential oil: An in silico and in vitro analysis

The essential oil (EO) derived from Curcuma angustifolia Roxb. has gained significant interest in traditional medicine, specifically for its potential as a therapeutic agent for inflammatory disorders. Our study aimed to identify the chemical constituents of C. angustifolia EO, investigate its anti-inflammatory effects in lipopolysaccharide (LPS)-treated RAW 264.7 cells and explore potential nitric oxide (NO) inhibitors through in silico based studies. The essential oil obtained through hydro-distillation underwent analysis via gas chromatography-mass spectrometry (GC-MS). The major constituents were identified as velleral (17.82 %), germacrone (12.91 %), cryptomerione (11.52 %), curzerene (5.66 %) and ?-elemene (4.09 %). The EO demonstrated non-toxicity up to a concentration of 50 µg/mL, maintaining over 70 % viability in RAW 264.7 cells. At a concentration of 25 µg/mL, treatment with C. angustifolia EO exhibited significant anti-inflammatory properties, leading to a 66 % decrease in LPS-induced NO production. Inducible nitric oxide synthase (iNOS) crystal structures were sourced from the RCSB database. Compounds identified through GC-MS analysis were retrieved from PubChem, docked by the molecular-docking process and tested for drug-likeness properties. The compounds such as velleral (-5.8 kcal/mol), germacrone (-5.4 kcal/mol), neocurdione (-5.2 kcal/mol) and ?-cadinene (-5.2 kcal/mol) exhibited the highest binding-affinity with iNOS. Molecular dynamics simulation (MDS) showed that the interaction of these 4 phyto-compounds was stable with the active site residues. Important bonds identified in the initial ligand-docked compounds persisted unaltered throughout the MDS. The present work with in vitro and in silico studies revealed that C. angustifolia EO could be a potential anti-inflammatory agent, thus necessitating further in vivo studies to develop promising therapeutic agents in the treatment of inflammation.